Two experiments are proposed. Each is designed to provide the background for a line of research aimed at examining the potential therapeutic effects of physical activity among individuals diagnosed with a mood disorder. This proposal considers the effect of exercise on emotional responsiveness in dysphoric individuals. The purpose of experiment one is to examine facial electromyographic (EMG), heart rate, blood pressure, and skin conductance responses during sustained periods of pleasant, neutral, and unpleasant picture viewing in dysphoric and non-dysphoric individuals who vary in their self-reported level of physical activity. It is predicted that dysphoric individuals will exhibit a blunted emotional responsiveness to arousing pleasant stimuli, and furthermore, that this effect will be greater among non-physically active individuals. The purpose of experiment two is to examine the effect of acute physical exercise, compared to a resting control condition, on psychophysiological responses during emotional picture viewing in dysphoric compared to non-dysphoric individuals. It is predicted that exercise will activate the appetitive emotional system in dysphoric individuals and restore appetitive emotional responsiveness. In addition, aerobic fitness is expected to be positively related to emotional responsiveness to both pleasant and unpleasant stimuli at baseline in both groups of individuals. The largest effect for restoring pleasant emotional responsiveness is expected to occur in the least aerobically fit dysphoric individuals.